As the 21st-century global economy increasingly hits natural resource limits and planetary boundaries, fundamental questions about fair shares will start to arise. How these arguments play out will exert a crucial influence over prospects for poor people and international development. Are aid donors, NGOs and other development opinion-formers paying attention?The massive increase in the price of food is hitting the poorest hardest. (Photograph: Krishnendu Halder/Reuters)

Demand for resources of all kinds – especially food, oil, land, water and "carbon space" for greenhouse gas emissions in the atmosphere – is growing exponentially. It's a logical consequence of the world's population continuing to grow, and the global middle class becoming larger and more affluent.

But even as demand grows, supply is struggling to keep up. The yield gains of the agricultural "green revolution" are running out of steam. Competition for land and water is intensifying. Investment in new oil production is inadequate to meet future demand, according to the International Energy Agency – even before peak oil is taken into account. Carbon space is acutely limited if the world is to limit global warming to anything like 2C.

Within many fragile states, disputes over access to land and water are becoming intense. In the process, they're increasing the threat of violent conflict, as the war in Darfur from 2003 to 2010 and low-intensity violence currently taking place in the Horn of Africa both show.

Internationally, the trend of "landgrabs" has seen 80m hectares (an area considerably larger than France) acquired in deals since 2001, with poor people all too often displaced from communal lands as a result. The same theme can be seen offshore, for instance in EU fishing fleets snapping up fishing rights off Senegal.

Fair shares issues are emerging in food markets as well. With the US now diverting 40% of its corn crop to biofuels and millions more consumers shifting to resource-intensive "western diets", food prices are soaring, slipping out of the reach of many of the world's poorest.

Or look at energy. Spiralling oil prices are squeezing poor, import-dependent countries out of the market: between 2004 and 2007, more than a dozen African countries spent more on oil imports than they received in aid and debt relief. In the world's mushrooming cities, electrical "load-shedding" (cutting off the electricity on some lines when the demand exceeds the supply) and brownouts (drops in voltage) tend to see poor consumers lose out most (if indeed they have access to electricity at all – 1.4 billion of them don't).

So how should aid donors and campaigners react?

First, they must recognise just how much of a game changer resource limits are for global fairness and equity agendas. Left and right have long disagreed about more or less everything, except the existence of an expanding "cake" to share out. But introduce limits to the equation – whether to particular resources, or to growth per se – and arguments over fair shares take on a much harder-edge.

Second, they should underline that fair shares for the poor is not just about justice. It's also a recognition of what it takes to co-exist in a massively interdependent world. If the world slides into a century of zero sum competition for scarce resources, everyone will lose from the resulting instability.

Facing up to the need for fair shares is also a prerequisite for managing global commons such as the atmosphere. Policymakers have spent two decades studiously ignoring the central question of how to share out a safe global carbon budget between 193 countries – with policy options that could provide the answer, such as Contraction and Convergence, left on the shelf for someone else's term of office. As a result of this failure to face up to the hard issues, greenhouse gas concentrations continue to climb higher every year.

Third, they should point to examples where policymakers and the public have embraced the principle of fair shares. Rationing in the second world war is the obvious case, but there are more interesting examples. In Alaska, for instance, all adult citizens receive an equal dividend payment from the state's oil and gas production each year.

Above all, they should recognise that the resource limits and fair shares agenda is primarily global. To be sure, there is much to be done within developing countries – from pushing for equitable natural resource governance regimes, to dramatically scaling up social protection provision that can help poor people to secure their basic needs.

But given that the key demand drivers for natural resources are global, the solutions have to be too. Unless developed countries and the "global middle class" dramatically reduce their consumption levels, not enough space will be left for the world's poorest countries and people. Ensuring that doesn't happen needs to become a top priority for supporters of development.

Alex Evans heads the resource scarcity program at New York University's Center on International Co-operation and co-edits the foreign policy website, Global Dashboard. He is the author of a new discussion paper on Resource Scarcity, Fair Shares and Development (pdf), published by WWF and Oxfam.

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